<template>
  <div>
    <div class="shopcart">
      <div class="content">
        <div class="content-left" @click="toggleShow">
          <div class="logo-wrapper">
            <div class="logo" :class="{highlight: totalCount}">
              <i class="iconfont icon-shopping_cart" :class="{highlight: totalCount}"></i>
            </div>
            <div class="num" v-if="totalCount">{{totalCount}}</div>
          </div>
          <div class="price" :class="{highlight: totalCount}">￥{{totalPrice}}</div>
          <div class="desc">另需配送费￥{{info.deliveryPrice}} 元</div>
        </div>
        <div class="content-right">
          <div class="pay" :class="payClass">{{payText}}</div>
        </div>
      </div>
      <transition name="move">
        <div class="shopcart-list" v-show="listShow">
          <div class="list-header">
            <h1 class="title">购物车</h1>
            <span class="empty" @click="clearCart">清空</span>
          </div>
          <div class="list-content">
            <ul>
              <li class="food" v-for="(food, index) in cartFoods" :key="index">
                <span class="name">{{food.name}}</span>
                <div class="price"><span>￥{{food.price}}</span></div>
                <div class="cartcontrol-wrapper">
                  <CartControl :food="food"></CartControl>
                </div>
              </li>
            </ul>
          </div>
        </div>
      </transition>
      
    </div>
    <transition name="fade">
      <div class="list-mask" v-show="listShow" @click="toggleShow"></div>
    </transition>
  </div>
</template>

<script>
  import {mapState, mapGetters} from 'vuex'
  import {MessageBox} from 'mint-ui'
  import BScroll from 'better-scroll'
  import CartControl from '../CartControl/CartControl'
  
  export default {
    name: "ShopCart",
    data() {
      return {
        isShow: false
      }
    },
    computed: {
      ...mapState(['cartFoods', 'info']),
      ...mapGetters(['totalCount', 'totalPrice']),
      payClass() {
        const {totalPrice} = this
        const {minPrice} = this.info
        return totalPrice >= minPrice ? 'enough' : 'not-enough'
      },
      payText() {
        const {totalPrice} = this
        const {minPrice} = this.info
        if (totalPrice === 0) {
          return `￥${minPrice}元起送`
        } else if (totalPrice < minPrice) {
          return `还差￥${minPrice-totalPrice}元起送`
        } else {
          return '去结算'
        }
      },
      listShow() {
        // 如果总数量为 0，直接不显示
        if (this.totalCount === 0) {
          // 不显示则将 this.isShow 置为 false
          this.isShow = false
          return false
        }

        // 应该在此处创建
        if (this.isShow) {
          // 显示就创建一个对象
          // -/+ 时所有创建的对象都会响应
          this.$nextTick(() => {
            // 实现 BScroll 的实例是一个单例
            if (!this.scroll) {              
              this.scroll = new BScroll('.list-content', {
                click: true
              })
            } else {
              // 列表在不断变化
              // 让滚动条刷新一下：重新统计内容的高度
              this.scroll.refresh() 
            }
          })
        }
        return this.isShow
      },
    },
    methods: {
      toggleShow() {
        // 只有当总数量大于 0时，才切换
        if (this.totalCount > 0) {
          this.isShow = !this.isShow
        }
      },
      clearCart() {
        MessageBox.confirm('确定清空购物车吗？').then(action => {
          this.$store.dispatch('clearCart')
        }, () => {})
      },
    },
    // 创建时机有问题，应该是显示时创建
    // watch: {
    //   cartFoods(value) {
    //     // console.log('watch cartFoods', value)
    //     new BScroll('.list-content')
    //     // 这个创建的 BScroll 不能完全满足要求（会弹回去）
    //     // 不需要使用 nextTick，当 cartFoods 有变化时就直接创建
    //     // this.$nextTick(() => {
    //     // })
    //   }
    // },
    components: {
      CartControl,
    },
  };
</script>

<style lang="less">
  @import '../../common/less/mixins.less';
  .shopcart {
    position: fixed;
    left: 0;
    bottom: 0;
    width: 100%;
    height: 48px;
    z-index: 50;
    .content {
      display: flex;
      background: #141d27;
      font-size: 0;
      color: rgba(255, 255, 255, .4);
      .content-left {
        flex: 1;
        .logo-wrapper {
          display: inline-block;
          position: relative;
          top: -10px;
          width: 56px;
          height: 56px;
          margin: 0 12px;
          padding: 6px;
          vertical-align: top;
          box-sizing: border-box;
          border-radius: 50%;
          background: #141d27;
          .logo {
            width: 100%;
            height: 100%;
            border-radius: 50%;
            text-align: center;
            background: #2b343c;
            &.highlight {
              background: @green;
            }
            .icon-shopping_cart {
              line-height: 44px;
              font-size: 24px;
              color: #80858a;
              &.highlight {
                color: #fff;
              }
            }
          }
          .num {
            position: absolute;
            top: 0;
            right: 0;
            width: 24px;
            height: 16px;
            line-height: 16px;
            text-align: center;
            border-radius: 16px;
            font-size: 9px;
            font-weight: 700;
            color: #fff;
            background: rgba(240, 20, 20, 1);
            box-shadow: 0 4p 8px 0 rgba(0, 0, 0, .4);
          }
        }
        .price {
          display: inline-block;
          margin-top: 5px;
          vertical-align: top;
          padding-right: 12px;
          box-sizing: border-box;
          font-size: 16px;
          line-height: 24px;
          font-weight: 700;
          color: #fff;
          &.highlight {
            color: #fff;
          }
        }
        .desc {
          display: inline-block;
          margin-bottom: 15px;
          margin-left: -45px;
          font-size: 10px;
          vertical-align: bottom;
        }
      }
      .content-right {
        flex: 0 0 105px;
        width: 105px;
        .pay {
          height: 48px;
          line-height: 48px;
          text-align: center;
          font-size: 12px;
          font-weight: 700;
          color: #fff;
          &.not-enough {
            background: #2b333b;
          }
          &.enough {
            background: #00b43c;
            color: #fff;
          }
        }
      }
    }
    .shopcart-list {
      position: absolute;
      left: 0;
      top: 0;
      width: 100%;
      z-index: -1;
      transform: translateY(-100%);
      &.move-enter-active,
      &.move-leave-active {
        transition: transform .3s;
      }
      &.move-enter,
      &.move-leave-to {
        // 隐藏到原始位置
        transform: translateY(0);
      }
      .list-header {
        height: 40px;
        line-height: 40px;
        padding: 0 18px;
        background: #f3f5f7;
        border-bottom: 1px solid rgba(7, 17, 27, .1);
        .title {
          float: left;
          font-size: 14px;
          line-height: 28px;
          color: rgba(7, 17, 27, 1);
        }
        .empty {
          float: right;
          font-size: 12px;
          color: rgba(0, 160, 220, 1);
        }
      }
      .list-content {
        padding: 0 18px;
        max-height: 217px;
        // height: 217px;
        overflow: hidden;
        // 这个会导致 bug（左边缺少一块）
        background: #fff;
        // margin-bottom: 56px;
        .food {
          position: relative;
          padding: 12px 0;
          box-sizing: border-box;
          .bottom-border-1px(rgba(7, 17, 27, .1));
          .name {
            line-height: 24px;
            font-size: 14px;
            color: rgba(7, 17, 27, 1);
          }
          .price {
            position: absolute;
            right: 90px;
            bottom: 12px;
            line-height: 24px;
            font-size: 14px;
            font-weight: 700;
            color: rgba(240, 20, 20, 1);
          }
          .cartcontrol-wrapper {
            position: absolute;
            right: 0;
            bottom: 6px;
          }
        }
      }
    }
  }
  .list-mask {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 40;
    backdrop-filter: blur(10px);
    opacity: 1;
    background: rgba(7, 17, 27, .6);
    &.fade-enter-active,
    &.fade-leave-active {
      transition: all .5s;
    }
    &.fade-enter,
    &.fade-leave-to {
      opacity: 0;
      background: rgba(7, 17, 27, 0);
    }
  }
</style>
